Unplugged Stepper and bypassed Temp sensor - car running muc
Discussion
I have now for a long time been trying to get my Griffith 500 (1997) to run properly. When accelerating I always felt as if it was hesitating. At some stage it was so bad that it was un-drivable. I found out that it was caused by air in the cooling system - venting cured the worst of the problem but the hesitant acceleration remained. I changed the temperatur sensor but no improvement.
I now tried to replace the temperature sensor with a 330 Ohm resistor and I also unplugged the stepper (with engine running and warm so it would remain in a good idle position) What a change - car running much smoother - accelerated continuously - idle more constant and I also noticed that it does not seem to get that warm. I guess there is a design flaw having the temperature sensor sitting in the highest point of the cooling system causing air to collect and giving false signals to the ECU. The only problem now it that the car is difficult to start when cold as the ECU believes the engine is warm.
Any suggestions or similar experience are welcome
Cheers
Dan
I now tried to replace the temperature sensor with a 330 Ohm resistor and I also unplugged the stepper (with engine running and warm so it would remain in a good idle position) What a change - car running much smoother - accelerated continuously - idle more constant and I also noticed that it does not seem to get that warm. I guess there is a design flaw having the temperature sensor sitting in the highest point of the cooling system causing air to collect and giving false signals to the ECU. The only problem now it that the car is difficult to start when cold as the ECU believes the engine is warm.
Any suggestions or similar experience are welcome
Cheers
Dan
The ECU doesn't think the engine is warm, as you mentioned it has coolant as well as fuel temp sensors to assess that. It simply cannot adjust the air / fuel mixture in the idle position.
Disconnecting the stepper motor means that the ECU is sending pulses to it to motor the shaft outwards and reduce the air coming into the system at idle, but it can't. There is no feedback loop to the ECU for stepper motor position so until the engine is warm, you are getting too much air in the air / fuel mixture making idle poor, or even impossible on a cold day.
I'd expect you would also get a rapid drop off in revs during gear changes and when coming to a stop at junctions, the stepper motor helps smooth that out, presuming it is getting the 'car moving' voltage from the speedometer box.
That said, quite a few people have done this and continue to do so. Some have struck lucky with a 'cheap' stepper. My £12 one was rubbish, car idled at 2000 rpm when stopping. A genuine one was £80 but sorted out my problems.
Disconnecting the stepper motor means that the ECU is sending pulses to it to motor the shaft outwards and reduce the air coming into the system at idle, but it can't. There is no feedback loop to the ECU for stepper motor position so until the engine is warm, you are getting too much air in the air / fuel mixture making idle poor, or even impossible on a cold day.
I'd expect you would also get a rapid drop off in revs during gear changes and when coming to a stop at junctions, the stepper motor helps smooth that out, presuming it is getting the 'car moving' voltage from the speedometer box.
That said, quite a few people have done this and continue to do so. Some have struck lucky with a 'cheap' stepper. My £12 one was rubbish, car idled at 2000 rpm when stopping. A genuine one was £80 but sorted out my problems.
dantvrgriff said:
I have now for a long time been trying to get my Griffith 500 (1997) to run properly. When accelerating I always felt as if it was hesitating. At some stage it was so bad that it was un-drivable. I found out that it was caused by air in the cooling system - venting cured the worst of the problem but the hesitant acceleration remained. I changed the temperatur sensor but no improvement.
I now tried to replace the temperature sensor with a 330 Ohm resistor and I also unplugged the stepper (with engine running and warm so it would remain in a good idle position) What a change - car running much smoother - accelerated continuously - idle more constant and I also noticed that it does not seem to get that warm. I guess there is a design flaw having the temperature sensor sitting in the highest point of the cooling system causing air to collect and giving false signals to the ECU. The only problem now it that the car is difficult to start when cold as the ECU believes the engine is warm.
Any suggestions or similar experience are welcome
Cheers
Dan
Going by what you have posted, by connecting a 330 Ohm resistor instead of the temp sensor you have managed to alter the ammount of fuel going into the engine and it runs goodI now tried to replace the temperature sensor with a 330 Ohm resistor and I also unplugged the stepper (with engine running and warm so it would remain in a good idle position) What a change - car running much smoother - accelerated continuously - idle more constant and I also noticed that it does not seem to get that warm. I guess there is a design flaw having the temperature sensor sitting in the highest point of the cooling system causing air to collect and giving false signals to the ECU. The only problem now it that the car is difficult to start when cold as the ECU believes the engine is warm.
Any suggestions or similar experience are welcome
Cheers
Dan
What you can now do is measure the resistance of a good temp sensor when cold and take note of the value
Once you have the resistance of a cold sensor please post it back here and I will post you all the information you will need for a minor modification
it is your choice as to what temperature you class as cold but there are ways around this
OK This will give you 1800 ohms to the ECU when cranking and 330 Ohms on run, this method will stop over fueling when cranking
You can play about with different resistances and if you wish you could have a couple of summer resistors and winter resistors pre-terminated so as to be able to quickly unplug 1 and plug in another
Another method is to wire a multi-position rotary switch to the dashboard and use it to select 1 of several resisistances to suit the climate at start-up and on run
You can play about with different resistances and if you wish you could have a couple of summer resistors and winter resistors pre-terminated so as to be able to quickly unplug 1 and plug in another
Another method is to wire a multi-position rotary switch to the dashboard and use it to select 1 of several resisistances to suit the climate at start-up and on run
For the sake of less than £20 bung a new temp sensor on. Maybe try a pan of water on the hob and see what it does compared to the old one, and confirm it does give you roughly 330 ohm at 80 degrees.
Stepper may well affect idle and starting but shouldn't mess up acceleration - it's possible you have two separate problems.
Stepper may well affect idle and starting but shouldn't mess up acceleration - it's possible you have two separate problems.
andy43 said:
For the sake of less than £20 bung a new temp sensor on. Maybe try a pan of water on the hob and see what it does compared to the old one, and confirm it does give you roughly 330 ohm at 80 degrees.
Stepper may well affect idle and starting but shouldn't mess up acceleration - it's possible you have two separate problems.
Stepper may well affect idle and starting but shouldn't mess up acceleration - it's possible you have two separate problems.
Something is very wrong here- Assuming the car has catalysts the ECU should correct the fuelling within about 30 seconds of starting the car- you can normally hear the engine note change once the lambdas lick in but you really need some sensor data to see whats going on and not guess-
If you are worried about the temp sensor, then measure the resistance of the water temp and fuel temp sensor on a cold engine- its the same device so the readings should be the same.
In terms of cold start fuelling, the TVR map does overdo it a bit due to its Land Rover origins, but a change of fuel map can be used with reduced fuelling if it grieves you that much . You can also frig about with the temperature values of the water sensor by putting a 10k variable resistor across it- and then using RoverGauge to see what cold temperature you want the ECU to see as you tweek the variable resistor. Due to the resistance curve of the thermistor the sensor uses, putting a resistor in parallel has a much bigger effect when the engine is cold, and very little when its hot, so you wont lean out the mixture and normal running temp so no need for relays or different resistors depending on the season- More to the point the ECU has software that control the injector timing depending on temp - so use this as it should be and all will be well.
If you are worried about the temp sensor, then measure the resistance of the water temp and fuel temp sensor on a cold engine- its the same device so the readings should be the same.
In terms of cold start fuelling, the TVR map does overdo it a bit due to its Land Rover origins, but a change of fuel map can be used with reduced fuelling if it grieves you that much . You can also frig about with the temperature values of the water sensor by putting a 10k variable resistor across it- and then using RoverGauge to see what cold temperature you want the ECU to see as you tweek the variable resistor. Due to the resistance curve of the thermistor the sensor uses, putting a resistor in parallel has a much bigger effect when the engine is cold, and very little when its hot, so you wont lean out the mixture and normal running temp so no need for relays or different resistors depending on the season- More to the point the ECU has software that control the injector timing depending on temp - so use this as it should be and all will be well.
Edited by blitzracing on Wednesday 3rd May 14:16
Penelope Stopit said:
OK This will give you 1800 ohms to the ECU when cranking and 330 Ohms on run, this method will stop over fueling when cranking
You can play about with different resistances and if you wish you could have a couple of summer resistors and winter resistors pre-terminated so as to be able to quickly unplug 1 and plug in another
Another method is to wire a multi-position rotary switch to the dashboard and use it to select 1 of several resisistances to suit the climate at start-up and on run
I posted the above as a suggestion as that is what the OP asked for and this method will give the OP what she/he needs to start the engine when coldYou can play about with different resistances and if you wish you could have a couple of summer resistors and winter resistors pre-terminated so as to be able to quickly unplug 1 and plug in another
Another method is to wire a multi-position rotary switch to the dashboard and use it to select 1 of several resisistances to suit the climate at start-up and on run
Obviously a professional fix with no addons is the best method
Thanks for your feedback and help guys.
What I am trying to solve is the hesitant acceleration. I always had the feeling that engine was not running free (since years). I did try to change the temperature sensor but with little effect. Then at one point the car became almost un-drivable (stalling and misbehaving) - somebody from this forum told me that it could be due to air in the cooling system - and venting actually solved the worst of the problem. This made me realise how sensible the ECU is to some air in the cooling system - I know it seems strange but .. . The temperature sensor sits in the highest point of the engine and when I replaced the sensor with a resistor the engine finally starting running better. I also noticed that the engine does not seem to get that warm. Now it could be that the real cause of the problem is somewhere else, but for now I think I will try the resistor in parallel or make myself a switch between 330 Ohm and 2000 Ohm for the temp sensor and eventually get hold of a new stepper motor (even though I like that the idle is finally consistent and that the engine immediately goes to idle when stopping - before it would always take a while before it would settle - clearly my stepper has an issue)
Cheers
What I am trying to solve is the hesitant acceleration. I always had the feeling that engine was not running free (since years). I did try to change the temperature sensor but with little effect. Then at one point the car became almost un-drivable (stalling and misbehaving) - somebody from this forum told me that it could be due to air in the cooling system - and venting actually solved the worst of the problem. This made me realise how sensible the ECU is to some air in the cooling system - I know it seems strange but .. . The temperature sensor sits in the highest point of the engine and when I replaced the sensor with a resistor the engine finally starting running better. I also noticed that the engine does not seem to get that warm. Now it could be that the real cause of the problem is somewhere else, but for now I think I will try the resistor in parallel or make myself a switch between 330 Ohm and 2000 Ohm for the temp sensor and eventually get hold of a new stepper motor (even though I like that the idle is finally consistent and that the engine immediately goes to idle when stopping - before it would always take a while before it would settle - clearly my stepper has an issue)
Cheers
As blitz says you need to get rovergauge or an ecumate on it to see what the sensors are telling the ecu.
Dead clever workaround there from PPitstop but it is a workaround that ideally shouldn't be necessary as these systems do work ok when fed the right information.
Are you on the right ecu map? Are you bridging the right temp sensor - tan coloured two pin plug? If it's running cooler is that because it's been running over hot due to poor fuelling or is the thermostat duff?
I would honestly get the rovergauge cable off the adverts section on here (I think it's blitz that sells them), buy a new temp sensor (brass bodied always used to be thought to be best quality?), get on ebay for a digital multimeter that can measure resistance, and see what's what - now the lucas software's been 'hacked' it's a no brainer. Less than an undred quid all in for all the above.
Says he who just chucked the lucas in the bin - emerald fitted by joolz
Dead clever workaround there from PPitstop but it is a workaround that ideally shouldn't be necessary as these systems do work ok when fed the right information.
Are you on the right ecu map? Are you bridging the right temp sensor - tan coloured two pin plug? If it's running cooler is that because it's been running over hot due to poor fuelling or is the thermostat duff?
I would honestly get the rovergauge cable off the adverts section on here (I think it's blitz that sells them), buy a new temp sensor (brass bodied always used to be thought to be best quality?), get on ebay for a digital multimeter that can measure resistance, and see what's what - now the lucas software's been 'hacked' it's a no brainer. Less than an undred quid all in for all the above.
Says he who just chucked the lucas in the bin - emerald fitted by joolz
dantvrgriff said:
Thanks for your feedback and help guys.
What I am trying to solve is the hesitant acceleration. I always had the feeling that engine was not running free (since years). I did try to change the temperature sensor but with little effect. Then at one point the car became almost un-drivable (stalling and misbehaving) - somebody from this forum told me that it could be due to air in the cooling system - and venting actually solved the worst of the problem. This made me realise how sensible the ECU is to some air in the cooling system - I know it seems strange but .. . The temperature sensor sits in the highest point of the engine and when I replaced the sensor with a resistor the engine finally starting running better. I also noticed that the engine does not seem to get that warm. Now it could be that the real cause of the problem is somewhere else, but for now I think I will try the resistor in parallel or make myself a switch between 330 Ohm and 2000 Ohm for the temp sensor and eventually get hold of a new stepper motor (even though I like that the idle is finally consistent and that the engine immediately goes to idle when stopping - before it would always take a while before it would settle - clearly my stepper has an issue)
Cheers
Hi DanWhat I am trying to solve is the hesitant acceleration. I always had the feeling that engine was not running free (since years). I did try to change the temperature sensor but with little effect. Then at one point the car became almost un-drivable (stalling and misbehaving) - somebody from this forum told me that it could be due to air in the cooling system - and venting actually solved the worst of the problem. This made me realise how sensible the ECU is to some air in the cooling system - I know it seems strange but .. . The temperature sensor sits in the highest point of the engine and when I replaced the sensor with a resistor the engine finally starting running better. I also noticed that the engine does not seem to get that warm. Now it could be that the real cause of the problem is somewhere else, but for now I think I will try the resistor in parallel or make myself a switch between 330 Ohm and 2000 Ohm for the temp sensor and eventually get hold of a new stepper motor (even though I like that the idle is finally consistent and that the engine immediately goes to idle when stopping - before it would always take a while before it would settle - clearly my stepper has an issue)
Cheers
Had much the same problems as you, along with a very unstable tick over it was getting to the point that having spent a lot of money on replacing parts I was ready to sell up because it was spoiling the driving experience that much.
In the end did what you have done and then blanked off the by-pass so the stepper can stay connected but does nothing. Have been like this for the last 5 years and have to say that it transformed the way it drives, even like the instant drop in revs while changing gear etc.
As you say the only problem is cold start which I am happy to live with. Cold start always throws a lot of fuel in so it always starts, the trick is to keep it running without needing to keep your foot on throttle, have tried a few manual ways to do this, but for me the simple solution is a short stick resting up against the pedal and seat bracket to hold 1800rpm while I shut garage, and run visual check by which time can remove the stick, store under the seat and away.
Andy
dantvrgriff said:
Thanks for your feedback and help guys.
What I am trying to solve is the hesitant acceleration. I always had the feeling that engine was not running free (since years). I did try to change the temperature sensor but with little effect. Then at one point the car became almost un-drivable (stalling and misbehaving) - somebody from this forum told me that it could be due to air in the cooling system - and venting actually solved the worst of the problem. This made me realise how sensible the ECU is to some air in the cooling system - I know it seems strange but .. . The temperature sensor sits in the highest point of the engine and when I replaced the sensor with a resistor the engine finally starting running better. I also noticed that the engine does not seem to get that warm. Now it could be that the real cause of the problem is somewhere else, but for now I think I will try the resistor in parallel or make myself a switch between 330 Ohm and 2000 Ohm for the temp sensor and eventually get hold of a new stepper motor (even though I like that the idle is finally consistent and that the engine immediately goes to idle when stopping - before it would always take a while before it would settle - clearly my stepper has an issue)
Cheers
This could be something as simple as a poor spark, so dont discount the ignition system or plug extenders.What I am trying to solve is the hesitant acceleration. I always had the feeling that engine was not running free (since years). I did try to change the temperature sensor but with little effect. Then at one point the car became almost un-drivable (stalling and misbehaving) - somebody from this forum told me that it could be due to air in the cooling system - and venting actually solved the worst of the problem. This made me realise how sensible the ECU is to some air in the cooling system - I know it seems strange but .. . The temperature sensor sits in the highest point of the engine and when I replaced the sensor with a resistor the engine finally starting running better. I also noticed that the engine does not seem to get that warm. Now it could be that the real cause of the problem is somewhere else, but for now I think I will try the resistor in parallel or make myself a switch between 330 Ohm and 2000 Ohm for the temp sensor and eventually get hold of a new stepper motor (even though I like that the idle is finally consistent and that the engine immediately goes to idle when stopping - before it would always take a while before it would settle - clearly my stepper has an issue)
Cheers
I actually do have the rover gauge software - the engine temperature always seemed right on there. Does anybody have some documentation on what the various readings should be ?
The only error message I keep getting is Throttle potentiometer but I have measured the throttle pot on an oszilloskop at work - seems perfect. I tried to pull a new cable from the ECU to the throttle pot thinking I could have an cable issue but without change.
I did change the brass brown temperature sensor 2 years ago thinking it would help - but no change. I will keep investigating and will try to connect the rover gauge again this weekend.
Changed spark plugs, distributor,leads, some of the extenders last year
It is like Andy said - at some stage you just get fed-up spending all your time looking and changing parts. There are these days where she runs beautiful and you really think - what a great car but a moment later she will start misbehaving. I test drove the new mustang - what and enjoyment to drive a modern V8 that just runs perfect. The Rover V8 is not bad - I guess it is just the ECU that is outdated.
Cheers
Dan
The only error message I keep getting is Throttle potentiometer but I have measured the throttle pot on an oszilloskop at work - seems perfect. I tried to pull a new cable from the ECU to the throttle pot thinking I could have an cable issue but without change.
I did change the brass brown temperature sensor 2 years ago thinking it would help - but no change. I will keep investigating and will try to connect the rover gauge again this weekend.
Changed spark plugs, distributor,leads, some of the extenders last year
It is like Andy said - at some stage you just get fed-up spending all your time looking and changing parts. There are these days where she runs beautiful and you really think - what a great car but a moment later she will start misbehaving. I test drove the new mustang - what and enjoyment to drive a modern V8 that just runs perfect. The Rover V8 is not bad - I guess it is just the ECU that is outdated.
Cheers
Dan
dantvrgriff said:
I actually do have the rover gauge software - the engine temperature always seemed right on there. Does anybody have some documentation on what the various readings should be ?
The only error message I keep getting is Throttle potentiometer but I have measured the throttle pot on an oszilloskop at work - seems perfect. I tried to pull a new cable from the ECU to the throttle pot thinking I could have an cable issue but without change.
I did change the brass brown temperature sensor 2 years ago thinking it would help - but no change. I will keep investigating and will try to connect the rover gauge again this weekend.
Changed spark plugs, distributor,leads, some of the extenders last year
It is like Andy said - at some stage you just get fed-up spending all your time looking and changing parts. There are these days where she runs beautiful and you really think - what a great car but a moment later she will start misbehaving. I test drove the new mustang - what and enjoyment to drive a modern V8 that just runs perfect. The Rover V8 is not bad - I guess it is just the ECU that is outdated.
Cheers
Dan
Hi DanThe only error message I keep getting is Throttle potentiometer but I have measured the throttle pot on an oszilloskop at work - seems perfect. I tried to pull a new cable from the ECU to the throttle pot thinking I could have an cable issue but without change.
I did change the brass brown temperature sensor 2 years ago thinking it would help - but no change. I will keep investigating and will try to connect the rover gauge again this weekend.
Changed spark plugs, distributor,leads, some of the extenders last year
It is like Andy said - at some stage you just get fed-up spending all your time looking and changing parts. There are these days where she runs beautiful and you really think - what a great car but a moment later she will start misbehaving. I test drove the new mustang - what and enjoyment to drive a modern V8 that just runs perfect. The Rover V8 is not bad - I guess it is just the ECU that is outdated.
Cheers
Dan
Would just like to add :-
Very happy with running without a stepper, feels nice and reliable with a very strong and consistant performance, before was never quite sure how the day would go, could be stalling everytime or sittng stationary with 1800 rpm idle or run all day without problems – the pain was that even on a good day I would be waiting for the problem to come back.
Anyway regarding your hesitatnt pick up – yes I had this as well, kind of like it bogged down on a trailing throttle so as you increased throttle a slight delay almost like waiting for it to clear, and then it would take off.
I changed the plugs from the standard shrouded racing type NGK B7ECS to a more everyday NGK BPR6ES which has transformed the pick up – it now feels very very crisp and improved throttle response by a big margin.
Hope you get it sorted, it is worth the trouble because at the other end there is nothing eles on the road like a well running TVR
Andy
dantvrgriff said:
I actually do have the rover gauge software - the engine temperature always seemed right on there. Does anybody have some documentation on what the various readings should be ?
The only error message I keep getting is Throttle potentiometer but I have measured the throttle pot on an oszilloskop at work - seems perfect. I tried to pull a new cable from the ECU to the throttle pot thinking I could have an cable issue but without change.
I did change the brass brown temperature sensor 2 years ago thinking it would help - but no change. I will keep investigating and will try to connect the rover gauge again this weekend.
Changed spark plugs, distributor,leads, some of the extenders last year
It is like Andy said - at some stage you just get fed-up spending all your time looking and changing parts. There are these days where she runs beautiful and you really think - what a great car but a moment later she will start misbehaving. I test drove the new mustang - what and enjoyment to drive a modern V8 that just runs perfect. The Rover V8 is not bad - I guess it is just the ECU that is outdated.
Cheers
Dan
The ECU works perfectly well if everything is as it should be- so we know the basic temp readings are OK- If you are getting throttle pot errors- you have a fault, no ifs no buts.They can go open circuit as they warm up, and that cuts the fuel as it thinks the car is on the over run. The ECU is smart enough to work out if you have a high airflow reading, so throttle cant be shut and it will throw an error also. Another thing to look at is the short and long term fuel trim- high +ve readings can mean a misfire.The only error message I keep getting is Throttle potentiometer but I have measured the throttle pot on an oszilloskop at work - seems perfect. I tried to pull a new cable from the ECU to the throttle pot thinking I could have an cable issue but without change.
I did change the brass brown temperature sensor 2 years ago thinking it would help - but no change. I will keep investigating and will try to connect the rover gauge again this weekend.
Changed spark plugs, distributor,leads, some of the extenders last year
It is like Andy said - at some stage you just get fed-up spending all your time looking and changing parts. There are these days where she runs beautiful and you really think - what a great car but a moment later she will start misbehaving. I test drove the new mustang - what and enjoyment to drive a modern V8 that just runs perfect. The Rover V8 is not bad - I guess it is just the ECU that is outdated.
Cheers
Dan
Everything document wise is here:
https://www.dropbox.com/sh/i0acxr8nwr10ow6/AAAIPux...
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